The present invention relates to an LED (light emitting diode) display unit used for forming an LED large-sized display panel or board for the outdoor.
An LED display unit of the kind referred to above is constructed as follows as shown in a front elevational view of FIG. 8 of the attached drawings and in a cross-sectional view of FIG. 9 thereof taken along a line IX--IX in FIG. 8. That is, a plurality of LEDs 2 are packaged on a printed circuit board 1, and portions of the respective LEDs 2 except for light-emitting sections thereof are sealed by a resin 3 to form an LED arrangement. The LED arrangement is received in, for example, a case 4 which is formed of a plastic material. A plurality of cases 4, in each of which the LED arrangement has been received, are arranged on an attaching plate 5 or are fixedly mounted on the attaching plate 5 by respective screws 6, thereby to form a large-sized display panel. In this connection, the reference numeral 7 denotes lead wires which extend rearwardly from the printed circuit board 1 through a back or rear wall of the case 4 and the attaching plate 5.
The above-described conventional LED display unit is of construction in which an entire back face of the case 4 is mounted on the attaching plate 5 in close contact therewith. For this reason, there is a problem that an efficiency of heat radiation from the back face of the case 4 is deteriorated so that portions of the LEDs 2 are liable to be heated to a high temperature. In the future, LED large-sized display panels for the outdoors, which are high in luminance or brightness and which are wide in viewing, will be required, and it will be required to package many more LEDs 2 onto the printed circuit boards 1. However, the LED display unit having the above-described construction will not be able to meet this requirement.